1. Field of the Invention
The present invention relates to a liquid filling apparatus applicable to a machine for canning beer and cola or the like.
2. Description of the Prior Art
In a well-known machine for filling a container with liquid, that is, in a well-known container filling machine, for example, as shown in FIG. 3, a large number of housings 1 are fixedly disposed in an annular array on the underside of an annular tank 32. To each housing 1 is externally fitted a cylindrical holding member 4 in an air-tight and liquid-tight manner.
FIGS. 4 and 5 schematically illustrate an elevator device for raising and lowering the holding member 4, which is mounted on the container filling machine.
As shown in these figures, the cylindrical holding member 4 is moved along an outer circumferential surface 2 of the individual housing 1 by a cylinder guide 6. The direction of its movement is indicated by an arrow 5. The holding member 4 is moved via the cylinder guide 6 in the vertical direction by a single-arm lever 7.
The lever 7 is pivotably supported at a pivot means 8 of a bracket provided on the filling machine. This lever 7 is pivotably mounted at its middle point 9 to an intermediate member 10. The intermediate member 10 is connected at the other end thereof to a bent lever arm 12 of a double-arm lever 13 via a pivot point 11. And, this two-arm lever 13 is supported by a pivot point 14 fixed relative to the filling machine. The pivot point 14 is the point at which the double-arm lever 13 is angulated. A longer lever arm 15 of this double-arm lever 13 is pushed by a compression spring 16 in the direction of an arrow 17, that is, in the upward direction as viewed in FIGS. 4 and 5 under a static condition. The compression spring 16 has its bottom end 18 supported by the filling machine. An end portion of the longer lever arm 15 of the lever 13 is positioned vertically via a roller 19 by means of a roller guide 20 of the filling machine.
The position of the lever device shown in FIG. 4 and the position of the same lever device shown in FIG. 5 are different from each other. In FIG. 4, the roller guide 20 is at its lowermost position, and accordingly the cylinder guide 6 assumes its highest position. In FIG. 5, the roller guide 20 occupies its uppermost position, and accordingly the roller 19 has been moved upwards by the compression spring 16 assuming an extended condition. The cylinder guide 6 is thus moved to its lowest position, and accordingly the holding member 4 is pressed against the mouth of a container (not shown).
Describing now this structure in more detail with reference to FIGS. 6 and 7, in these figures reference numeral 21 designates a part of the filling machine, specifically a bracket provided at the above-described annular tank 32. This bracket is provided with bearing bolts 22 and 23. The bearing bolt 22 corresponds to the pivot means 8 in FIG. 4 or 5, and the bearing bolt 23 corresponds to the pivot point 14.
More particularly, the roller 19 is connected via a mount bolt 24 to the longer lever arm 15 of the double-arm lever 13. To this longer lever arm 15 is mounted another bolt 25, and a support plate 26 for supporting the compression spring 16 is mounted to this bolt 25 so as to be rotatable about the bolt 25. Another support plate 27 for supporting the bottom end 18 of the compression spring 16 is mounted in a recess 28 of the bracket 21. It is to be noted that reference numeral 46 in FIG. 6 designates a pipe forming one constituent element of a liquid valve as will be described later, and numeral 49 designates a compression spring for upwardly biasing the same pipe 46.
Next, a filling apparatus in the prior art will be explained with reference to FIG. 3, by way of example, on the basis of disclosure in Japanese Patent Publication No. 56-32198 (1981).
A filling apparatus shown in FIG. 3 comprises a housing 1 threadedly fixed to the underside of a hollow annular tank 32 having a circular shape. Liquid to be poured into a container 34 is accommodated within the annular tank 32 and is subjected to gas pressure. A surface of the liquid is maintained below a top wall of the annular tank 32 so that gas can extend above the liquid surface. On the outside of the housing 1 is slidably mounted a holding member 4 which is formed as a hollow cylinder and serves to position and seal the container 34. The holding member 4 is held in tight contact with the outer surface of the housing 1 at a location indicated by reference numeral 35. The holding member 4 is also provided with a recessed portion (reference numeral 36 in FIG. 6) which can be engaged with a lever (reference numeral 7 in FIGS. 4-7) for vertically moving this holding member 4 with respect to the housing 1. The holding member 4 defines a positioning tapered surface 37 on the inner wall of its bottom portion 4c. At the top portion of the positioning tapered surface 37 is disposed a sealing element 38 for sealing the container 34. The container 34 is placed on a lower support table 39 which is fixed to the housing 1, and it is restrained at a position centered with respect to the filling apparatus by means of a guide member 40 having a semi-circular shape.
The housing 1 has an inner piece 41 therewithin, and between the inner piece 41 and the housing 1 is defined a nearly annular liquid feed passageway 42. This liquid feed passageway 42 is interrupted at one location by a connecting bridge between the housing 1 and the inner piece 41. The diameter of the liquid feed passageway 42 is larger at its bottom portion 42a owing to a conical injection port 42b which directs a liquid jet to an inner wall surface of the container 34, whereupon the liquid flows down towards the bottom portion of the container while forming a laminar flow as much as possible.
The housing 1 has a stepped portion 43 on the inside forming an upper limit of the inner piece 41. The top end of the gap forming the liquid feed passageway 42 terminates there, and as the gap must be sealingly closed there, an annular sealing element 44 is disposed above the stepped portion 43. Sealing element 44 can be vertically moved by a pipe 46 provided with a hole 45. Among these respective members, the housing 1, the inner piece 41, the annular sealing element 44 and the pipe 46 jointly constitute a liquid valve. A compression spring 49 is disposed around the pipe 46, and this spring 49 is compressed between an inner wall (not shown) of the annular tank 32 and a flange mounted to an upper portion of the pipe 46. An inner space and an outer space 50 communicate with a liquid space 33 within the annular tank 32. At the central portion of the inner piece 41 is fixed a gas passage pipe 56. A gas pipe 51 is disposed within the same gas passage pipe 56 so as to be movable in the axial direction. The gas pipe 51 has at its bottom portion a recess 51a extending along the outer circumferential surface thereof. A tip end portion 127a of a bent member 127 is mounted to the gas pipe 51 within recess 51a. The bent member 127 is connected at the other end 29 thereof to the holding member 4 by means of a screw 30.
The gas pipe 51 extends into an inner space 57 of the gas passage pipe 56, so as to be movable in the axial direction. The gas passage pipe 56 extends upwards into the gas space within the annular tank 32 and terminates above the liquid surface. Consequently, the inner space 57 of the gas space within the annular tank 32. In the gas passage pipe 56 is disposed a gas valve (not shown).
An outer surface la of the housing 1 and an inner surface 4a of the holding member 4 are respectively provided with annular shoulders 1b and 4b, and these form a pressure chamber 59. The cylindrical pressure chamber 59 communicates with the inner space of the container 34 via a passageway 63, and further communicates with a normally closed release valve 61 via still another release passageway 62. The release valve 61 is closed under a rest condition, and it comprises a valve seat 64, and a valve body 66 which is urged against the valve seat 64 by a spring 65. A tapet 60 is connected to the valve body. This tapet projects beyond the outer circumference 67 of the annular tank 32, and is actuated by a cam track.
The diameters of the outer circumference of the housing 1 and the inner circumference of the main portion of the holding member 4 are larger than the inner diameter of the container 43 and the diameter of its flared open portion. The housing 1 is fixedly disposed, and furthermore, its inner piece 41 is not relatively movable with respect to the container 34. Accordingly, the annular cross section of the pressure chamber 59 is larger than the cross-sectional area within the container which falls between the inner diameter of the sealing element 38 and the outer diameter of the housing 1.
The above-described filling apparatus operates as follows.
Under a rest condition, since the liquid valve 47 including the housing 1, the inner piece 41, the annular sealing element 44 and the pipe 46 is closed, liquid cannot flow out. The space located inwardly of the gas passageway pipe 56 is likewise closed by a gas valve (not shown). The release valve 61 is also closed. An empty open-ended container 34 is carried into the apparatus by a conveyor device (not shown), or is conveyed onto the lower support table 39, and is centered with respect to the filling apparatus by means of the guide member 40. Subsequently, the filling apparatus and the container do not move relative to one another, but together undergo a circular motion within the entire filling machine.
The holding member 4 is moved downwards by the lever 7 engaged within the above-described recess 36 of the holding member 4 and engages the container 34. A gas valve (not shown) in the gas passage pipe 56 is opened by a control device (also not shown), and gas flows for the annular tank 32 through the gas passage pipe 56 and the gas pipe 51 and reaches the interior of the container 34. Therefore, the pressures within the container 34, in the liquid feed passageway 42, in the passageways 62 and 63 and in the pressure chamber 59 are equal because these spaces all communicate with one another. Because this pressure acts upon the bottom of the pressure chamber 59 (surface 4b), a slight over-pressure is present due to a difference between the diameter of surface 4b and the container sealing diameter. Accordingly, the pressure of the gas fed through the gas pipe 51 is the decisive one for establishing sealing pressure. After pressure equilibrium has been attained, the liquid valve 47 is automatically opened against the action of the spring. Consequently, liquid passes through the liquid feed passageway 42 and reaches the inside of the container 34. Liquid is poured into the container 34 until the liquid surface reaches the mouth portion of the gas pipe 51. As the other valves are closed, the gas existing at an upper portion of the container cannot escape, and therefore, further filling of the container becomes impossible. The liquid valve 47 and a gas valve (not shown) in the gas passage pipe 56 are mechanically closed by a control device (also not shown) and the interior of the container 34 is perfectly sealed from the interior of the annular tank 32 and from the outside atmosphere.
Subsequently, the release valve 61 is opened by a cam, and the pressure in the interior of the container 34 is released through the passageway 63, the pressure chamber 59, the passageway 62 and the release valve 61. After the pressure release has been effected, the holding member 4 is raised from the edge of the container 34, jointly with the sealing element 38, the bent member 127 and the gas pipe 51. In succession, the container 34 is transferred from a rotary zone of the filling machine to a rotary circle zone of a closing machine (not shown).
Recently, however, there are a number of diverse containers being used and containers have thinner walls than ever before. Especially when a container made of light and easily deformable material, such as aluminum, is filled there is a possibility that the container may be crushed or deformed. If such a situation were to arise, it would be impossible to appropriately fill the container. And, because aluminum cans having thin walls have become more prevalent in the industry, there is the need for a filling apparatus which can seal a container while suppressing the force acting upon a side wall of the container to minimum.
In order to fulfill such a need, this invention solves the following three problems in the prior art:
(1) According to the above-described holding member elevator device (FIGS. 4, 5, 6 and 7) in the prior art, when the holding member 4 descends towards the container 34, a compression spring 16 is used to effect a seal between the sealing element 38 and the container. The output of this spring is transmitted by a link-lever mechanism to the holding member 4, and a sealing force is exerted between the container flange and the sealing element 38. This linklever mechanism is a so-called toggle type linkage, in which if the angle formed between the intermediate member 10 and the arm 12 is 180.degree. , then a force acts on the container which is larger than the force generated by the compression spring 16. And so, this mechanism cannot always be said to be advantageous for use in the age of aluminum thin-walled containers.
(2) Also, according to the above-described holding member elevator device (FIGS. 4, 5 and 6) in the prior art, the arm member (lever 7) fixedly fitted to the holding member 4 is engaged with the bracket 21 of the holding member elevator device via pins and the like. Therefore, when the gas pipe 51 is replaced, first the holding member elevator device must be removed from the container filling machine. Next, the gas pipe 51 is dismounted and another gas pipe 51 corresponding to a new container 34 is mounted. Then, the holding member elevator device is mounted again. Such troublesome and numerous operations must be carried out for every filling valve which consequently contributes to low production efficiency.
(3) In the above-described prior art apparatus, the outer diameter of the housing at the annular seal member provided on the inner wall of the holding member is larger than the diameter of the container flange. Therefore, when a counter-pressurizing gas is introduced through the gas pipe while the container opening portion butts against the container sealing element, a force, corresponding to the area between the above-mentioned outer diameter of the housing and the inner diameter of the container flange, acts upon the side wall of the container via the peripheral edge of the container opening. When filling a can with a beverage under a high counterpressure such as that necessary for soda pop, cola, or the like, a correspondingly intensified force acts upon the container. This is disadvantageous in the age of thin-walled aluminum containers.
Moreover, with regard to the above-described third point (3), in order to adapt the filling machine to diverse containers, the diameter of the outer circumference of the housing, and hence, the inner diameter of the holding member must correspond to a flange diameter of each type of container.